Methods for making slip resistant file folders

ABSTRACT

Methods for producing easily and securely gripped slip-resistant file folders, including file pockets and hanging folders. The methods include providing folder paper stock; conveying the folder paper stock in the process of folder manufacture; providing a curable slip-resistant material in a melt state; applying the slip-resistant material at predetermined areas of the folder paper stock; and curing the slip-resistant material; such that the slip-resistant portion comprises cured slip-resistant material. Another method includes providing folder paper stock; providing embossing dies in spaced, operable, mating relationship; positioning the folder paper stock appropriately in the embossing dies; applying force to at least one of the embossing dies so as to decrease the spaced relationship; and deforming the folder paper stock.

This application is a divisional of and claims priority to U.S. Ser. No.09/463,229 entitled Slip Resistant File Folders, priority date Dec. 18,1997.

FIELD OF THE INVENTION

This invention relates to improvements in file folders, expandablefolders, hanging folders, and the like.

BACKGROUND OF THE INVENTION

File folders have become a necessity in today's modern offices andbusinesses. Such folders may be as simple as stiff, folded paperboard,often having predetermined cut out or raised areas for attaching labelsor other identifying indicia. File folders, such as manila folders, areuseful for storing paper and related articles in an orderly manner infile drawers or cabinets. Many improvements have been made to the simplefile folder, including expandable folders that can hold a large amountof papers, reinforced edges for stronger, longer lasting use, and claspmeans for positively securing the file contents so that enclosed papersstay organized and do not fall out.

Many variations of the simple file folder are known. For example “filepockets” are expandable file folders having fan-folded sides for highercapacity storing of papers. File pockets come in a variety of sizes,including letter and legal size. “Expanding files” are similar to filepockets, but generally have a flap attached that can be secured to afront cover to prevent papers from falling out the top of the file.Expanding files often have numerous pockets inside which are sometimesindexed for added organizational capability. Closely related toexpanding files are expanding wallets, which generally have an elasticcord attached to the flap which can be used to secure the flap in aclosed position.

In addition to simple file folders, file pockets, expanding files andexpanding wallets, it is known to use hanging folders for receiving filefolders and the like. Hanging folders are made for use in standardstorage units such as file cabinets, desk drawers and the like. Hangingfolders are generally formed of a sheet of heavy weight paper with acentral horizontal fold which forms the folder's bottom and has opensides. Folds are provided in the file's top edges through which hangingrods are movably or immovably fixed. The ends of these rods are exposedand notched, enabling the file to hang on a complementary standardparallel file frame in office storage equipment, such as filing cabinetsand desk drawers.

Improvements to hanging folders include providing the inner surfaces ofthe folded over portions at the top of each flap with uniformly spacedslots for insertion of labeling tabs. Reinforcing plastic film may beapplied to the exposed edges to reduce wear as the file is moved in theframe or file drawer. This film may be applied with colored adhesive toprovide a color coding system or a clear film may be applied over acolored surface by clear adhesive to achieve the same result. Hangingfolders with strong, flat bottoms have been made to handle oversized orheavy contents. Other various improvements to hanging folders areexemplified in the art, including various means for attaching labeling,as well as adapting the hanging folder concept for a wide variety ofarticles, such as hanging loose-leaf ring binders.

One drawback to existing file folders and hanging folders is therelative difficulty in removing such folders from file drawers, filecabinets, and the like, especially when such folders are oversized, suchas relatively full expandable folders or full flat-bottom (box-bottom)hanging folders. It is often necessary to remove a folder to inspect,remove, or add to its contents, and it is often necessary to remove anentire file pocket or hanging folder for similar reasons. Removal isgenerally accomplished by gripping the top edges of the folder andlifting it out of the drawer. However, it is difficult to grip the topof a very full, thick, folder to remove it from the file drawer withoutit slipping, possibly falling and spilling its contents. This is becausethe paper stock used for existing folders is generally very smooth, andsomewhat slick, requiring the person removing the file to exertextremely high pressures to lift the folder. Even pulling a relativelythin file folder or hanging folder out of a full drawer is made moredifficult by the pressure of adjacent files. Often it is necessary touse two hands to grip a folder for removal. This problem is especiallypronounced for older persons, persons having arthritis, or personsotherwise being incapable of applying sufficient grip strength.

Accordingly, it would be desirable to have a slip-resistant file folder,hanging folder, and the like, that is easy to grip and remove from itsdrawer or cabinet.

Additionally, it would be desirable to be able to adapt an existing filefolder, hanging folder, and the like, to be slip-resistant for easierremoval from a drawer or cabinet.

Additionally, it would be desirable to be able to economically produceslip-resistant file folders, hanging folders, and the like.

SUMMARY OF THE INVENTION

Methods for producing easily and securely gripped slip-resistant filefolders, including file pockets and hanging folders are disclosed. Themethods include providing folder paper stock; conveying the folder paperstock in the process of folder manufacture; providing a curableslip-resistant material in a melt state; applying the slip-resistantmaterial at predetermined areas of the folder paper stock; and curingthe slip-resistant material; such that the slip-resistant portioncomprises cured slip-resistant material. Another method includesproviding folder paper stock; providing embossing dies in spaced,operable, mating relationship; positioning the folder paper stockappropriately in the embossing dies; applying force to at least one ofthe embossing dies so as to decrease the spaced relationship; anddeforming the folder paper stock.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed that thepresent invention will be better understood from the followingdescription in conjunction with the accompanying Drawing Figures, inwhich like reference numerals identify like elements, and wherein:

FIG. 1 is a perspective view of a typical file folder, such as a manilafolder having a slip resistant portion disposed upon at least one flap;

FIG. 2 is a perspective view of a person gripping a folder of thepresent invention at the top for removal such as by lifting out of adrawer or cabinet;

FIG. 3 is a partial cut away view along Section 3-3 shown in FIG. 2,showing a slip-resistant portion in the form of a slip-resistant memberaffixed to a flap of the folder;

FIG. 4 is a partial cut away view, similar Section 3-3 shown in FIG. 2,showing another embodiment of a slip-resistant portion in the form of aslip-resistant member affixed to a folder;

FIG. 5 is a partial cut away view depicting another embodiment of aslip-resistant portion, namely a raised, embossed area;

FIG. 6 is a side view of three file folders of the present inventionshowing vertically-offset slip resistant portions;

FIG. 7 is a perspective view of a file pocket showing another embodimentof a slip-resistant portion of the present invention;

FIG. 8 is a perspective view of an expanding file showing anotherembodiment of a slip-resistant portion of the present invention;

FIG. 9 is a perspective view of a hanging folder showing anotherembodiment of a slip-resistant portion of the present invention;

FIG. 10 is a perspective view of a flat-bottom hanging folder showingstill another embodiment of a slip-resistant portion of the presentinvention;

FIG. 11 is a schematic illustration of an apparatus and process forproducing folders of the present invention;

FIG. 12 is a schematic illustration of an alternative apparatus andcontinuous process for producing folders of the present invention;

FIG. 13 is a schematic illustration of an alternative apparatus forproducing folders of the present invention;

FIG. 14 is a schematic illustration of an alternative process forproducing folders of the present invention;

FIG. 15 is a perspective view of a file pocket showing anotherembodiment of a slip-resistant portion of the present invention; and

FIG. 16 is a perspective view of a file pocket showing anotherembodiment of a slip-resistant portion of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, when used alone, the term “folder” encompasses all of“file folders”, “file pockets”, “expanding files”, “expanding wallets”,and “hanging folders” as well as other folding articles that may bestored in a file drawer or cabinet, such as hanging ring binders, boundpresentation folders, and the like.

As used herein, the term “file folder” means folders such as manila,kraft, pressboard, or plastic, typically supplied in letter or legalsize. File folders come in a variety of “points”, which denote theweight of the paper stock used for the folder. File folders are suppliedwith various improvements, such as color coding, undercut tabs forlabeling, reinforcing strips along edges, and fasteners to hold papersattached in various positions. By way of example, a manila file foldersuitable for the present invention is the Smead 152L heavyweight 11 pt.manila folder, available from the Smead company, Hastings, Minn.

As used herein, the term “file pockets” means expandable pockets havingfan-folded sides and a fan-folded bottom, useful for large files. Filepockets have a larger capacity than file folders, and may be used instandard filing systems, including hanging files. By way of example, afile pockets suitable for the present invention is the Wilson Jones 64series 3-½ inch expansion COLORLIFE® file pocket, from the Wilson JonesCompany, or the Smead 1524E Redrope® Pockets. File pockets are oftenreinforced to provide maximum durability and capacity.

As used herein, the term “expanding files” means expandable filingfolders, generally having a fan-folded bottom, full fan-folded sides,and a fold-over flap that is used to securely close the file. By way ofexample, an expanding file suitable for the present invention is the21-pocket Smead DR117A expanding file with flap, available from theSmead company.

As used herein, the term “expanding wallets” means expandable filingfolders similar to expanding files. Expanding wallets generally haveelastic cord tie flaps for securely closing a top flap. By way ofexample, expanding wallets suitable for the present invention includethe Oxford Plus® 60343 3-½ inch expansion reinforced wallets.

As used herein, the term “hanging folder” means folders designed for usewith hanging file systems. Such folders come in many variationsincluding box-bottom, expandable, color-coded, and reinforced-edge,durable designs. By way of example, hanging folders suitable for thepresent invention include standard size folders such as the EsseltePendaflex® 4152 series (letter size) and 4153 series (legal size)folders; box bottom folders such as the Esselte Pendaflex® 4152X series(letter size) and 4153X series (legal size) folders; expanding filepockets such as the Smead 18H24ESS (letter size) and 18H26ESS (legalsize) folders; and hanging expanding folders” as well as other foldingarticles that may be stored in a file drawer or cabinet, such as hangingring binders, bound presentation folders, and the like.

As used herein, the term “file folder” means folders such as manila,kraft, pressboard, or plastic, typically supplied in letter or legalsize. File folders come in a variety of “points”, which denote theweight of the paper stock used for the folder. File folders are suppliedwith various improvements, such as color coding, undercut tabs forlabeling, reinforcing strips along edges, and fasteners to hold papersattached in various positions. By way of example, a manila file foldersuitable for the present invention is the Smead 152L heavyweight 11 pt.manila folder, available from the Smead company, Hastings, Minn.

As used herein, the term “file pockets” means expandable pockets havingfan-folded sides and a fan-folded bottom, useful for large files. Filepockets have a larger capacity than file folders, and may be used instandard filing systems, including hanging files. By way of example, afile pockets suitable for the present invention is the Wilson Jones 64series 3-½ inch expansion COLORLIFE® file pocket, from the Wilson JonesCompany, or the Smead 1524E Redrope® Pockets. File pockets are oftenreinforced to provide maximum durability and capacity.

As used herein, the term “expanding files” means expandable filingfolders, generally having a fan-folded bottom, full fan-folded sides,and a fold-over flap that is used to securely close the file. By way ofexample, an expanding file suitable for the present invention is the21-pocket Smead DR117A expanding file with flap, available from theSmead company.

As used herein, the term “expanding wallets” means expandable filingfolders similar to expanding files. Expanding wallets generally haveelastic cord tie flaps for securely closing a top flap. By way ofexample, expanding wallets suitable for the present invention includethe Oxford Plus® 60343 3-½ inch expansion reinforced wallets.

As used herein, the term “hanging folder” means folders designed for usewith hanging file systems. Such folders come in many variationsincluding box-bottom, expandable, color-coded, and reinforced-edge,durable designs. By way of example, hanging folders suitable for thepresent invention include standard size folders such as the EsseltePendaflex® 4152 series (letter size) and 4153 series (legal size)folders; box bottom folders such as the Esselte Pendaflex® 4152X series(letter size) and 4153X series (legal size) folders; expanding filepockets such as the Smead 18H24ESS (letter size) and 18H26ESS (legalsize) folders; and hanging expanding files such as the Globe-WeisGlobalFile® 85030 expanding hanging file. A further example of hangingfolders of the type useful for the present invention is disclosed inU.S. Pat. No. 5,275,439 to Hawes, Jr. et al., issued Jan. 4, 1994.

As used herein, “high coefficient of friction” means a coefficient offriction between a folder and a person's fingers that is sufficient toresist slippage of the folder from the person's grip when lifting afolder out of a file drawer. It is acknowledged that sufficient frictionwill depend on a variety of factors, including a person's grip and theweight of the folder, as well as other environmental factors such asrelative humidity. For this reason, “high coefficient of friction” isnot meant to denote any absolute number or level, but is generallysubstantially higher than the coefficient of friction between typicalfolder paper stock and a user's fingers when gripping a folder from thetop. It is otherwise simply descriptive in principle of the desiredcharacteristic of a suitable material (or paper configuration) for useas the slip-resistant portion of the present invention. In other words,whether a material is applied as the slip resistant member, or the paperis deformed, e.g., as by embossing, the effect is an increase in thefrictional force between the folder and the user's fingers. The increasecan be due to an actual increase in the coefficient of friction due toaddition of a material such as a light tack adhesive, or it can be dueto a change in normal forces due to a change in folder geometry, such asby embossing.

A typical embodiment of a folder 10 of the present is shown in FIG. 1,which shows a file folder 20. File folder 20 has a front flap 22hingedly connected to a rear flap 24 at folder bottom 26 along a medialfold. In use, folder bottom 26 is disposed horizontally, generallyparallel to top edges 25. According to the present invention, filefolder 20 also has a slip-resistant portion 1 disposed on at least oneflap, but preferably on both the front flap 22 and rear flap 24.Slip-resistant portion 1 can be disposed as a horizontal band ofmaterial affixed near top edges 25. As shown below, the purpose ofslip-resistant portion 1 is to provide a region of the folder with ahigh coefficient of friction to allow easier slip-resistant gripping ofthe folder for lifting the folder from its drawer.

Slip-resistant portion 1 may comprise a variety of materials,configurations, patterns, and positions, but in general, the purpose ofthe slip-resistant portion is to provide a region of the folder having ahigh coefficient of friction between a user's fingers and the folder asit is being removed from a file drawer. For this reason, theslip-resistant portion can be comprised of a slip-resistant material,such as a light-tack adhesive that has a high coefficient of friction. Awide range of adhesives may be used, but in a preferred embodiment theslip-resistant portion comprises a permanently tacky pressure-sensitiveadhesive. By “pressure sensitive” is meant that the adhesives of theinvention are tacky to the touch at room temperature (e.g., about 20degrees C.), as can be readily determined by a finger tack test, and caneasily form a useful adhesive bond with the application of lightpressure. Pressure-sensitive adhesives are commonly used for adhesivetapes and labels, often with release liners for ease of delivery andapplication. Pressure sensitive adhesives may be rubber-based oracrylic/acrylate-based, with or without tackifiers added to impart tackor stickiness. In a preferred embodiment the slip-resistant portion isapplied in the hot melt state and allowed to cure to a light tack duringfolder manufacture. Typical recipes for such adhesives are shown in theEncyclopedia of Polymer Science and Engineering, Herman F. Mark, Ed.,1988, Vol. 13, under the heading Pressure Sensitive Adhesives andProducts, which section is hereby incorporated herein by reference. Inaddition to the adhesive properties, the placement and pattern of theslip-resistant portion also contributes to its performance.

A currently preferred pressure sensitive adhesive for use as theslip-resistant portion of the present invention is a removable adhesivesuch as the pressure sensitive adhesive having a low tack utilized onPost-it® notes. For example, a suitable adhesive is an acrylatecopolymer which is described in U.S. Pat. No. 3,691,140, issued Sep. 12,1972 to S. F. Silver, assigned to the Minnesota Minling & ManufacturingCo. of St. Paul, Minn., and improvements thereof. The adhesive isdescribed as having infusible solvent-dispersible, solvent-insoluble,inherently tacky, elastomeric copolymer microspheres consistingessentially of about 90 percent by weight of at least one alkyl acrylateester and about 10 to about 0.5 percent by weight of at least onemonomer selected from the group consisting of substantiallyoil-insoluble, water-insoluble, ionic monomers and maleic anhydride. Themicrospheres are prepared by aqueous suspension polymerization utilizingemulsifier in an amount greater than the critical micelle concentrationin the absence of externally added protective colloids or the like. Thedisclosure of the above-mentioned Silver '140 patent is herebyincorporated herein by reference.

Improvements to acrylate copolymer adhesives include improvements to theprocessibility of the adhesive. In particular, such adhesives have beenimproved to take advantage of the procedural, economical andenvironmental advantages of a hot melt processible adhesive. Forexample, an adhesive suitable for use as the slip-resistant material ofthe present invention is an acrylic pressure sensitive adhesive whichdisplays a superior balance of tack, peel strength and cohesive strengthfor hot melt processing as disclosed in U.S. Pat. No. 5,552,451, issuedSep. 3, 1996 to Everaerts et al., assigned to the Minnesota Mining &Manufacturing Co. of St. Paul, Minn., the disclosure of which is herebyincorporated herein by reference. The adhesive is described as apermanently removable, low melt viscosity acrylic pressure-sensitiveadhesive having three components: (1) at least one lower alkyl acrylatehaving an alkyl group which comprises from about 4 to 12 carbon atoms,(2) at least one higher alkyl acrylate having an alkyl group whichcomprises from about 12 to 26 carbon atoms and (3) sufficientcrosslinker to impart cohesive strength to the adhesive. Such removablepressure-sensitive adhesives, depending upon the viscosity, can becoated via any of a variety of conventional coating methods, such asroll coating, knife coating, hot melt coating, or extrusion.

In a preferred embodiment, the pressure sensitive adhesive used as theslip-resistant portion of the present invention has very light tack, or“stickiness”. Additionally, it is believed to be advantageous to have aremovable pressure sensitive adhesive having excellent shear strength,and reduced adhesive transfer to a person's fingers upon gripping andreleasing a folder of the present invention. Such an adhesive isdisclosed in U.S. Pat. No. 5,663,241 issued Sep. 2, 1997 to Takamatsu etal., assigned to the Minnesota Mining & Manufacturing Co. of St. Paul,Minn., the disclosure of which is hereby incorporated herein byreference. The disclosed adhesive comprises polyhydrazide tomicroparticles, producing an adhesive having excellent shear strength,and reduced adhesive transfer.

Alternatively, other high coefficient of friction polymeric materials,such as rubber-based adhesives (e.g., contact cement), or polymericmaterials, for example low durometer polyurethane, may be applied inways known in the art. Additionally, as shown below, the slip-resistantportion may be affixed in tape form to folders or formed by permanentlydeforming the flaps of the folder, such as by embossing. Whetheraffixed, applied, or formed by embossing, the slip-resistant portion ispreferably an integral part of the folder. However, it is contemplatedthat a removable slip-resistant portion may be desirable, such that itmay be removed by the user if unwanted. A slip-resistant portioncomprising removable double-back tape may be removed if desired.

Slip resistant portion 1 can also be formed integrally with the folderby mechanical methods such as embossing. Embossing can be accomplishedby pressing the folder between embossing dies, such as those describedwith reference to FIG. 13 below. Embossing is believed to advantageouslyincrease the frictional force between the folder and a user's fingers byproviding ridges or other such deformations for gripping. Furtheradvantages of embossing are described with respect to the FIGS. below.

As shown in FIG. 2, the advantage of the present invention is that thefolder 10, especially a thick folder or a hanging folder with manypapers enclosed, may be gripped easily and securely for removal from itsdrawer or cabinet. As shown, slip-resistant portion 1, here shown asembossed ridges, is preferably positioned such that as a person's hand 2grips the folder from the top, the user's fingers (not shown) and thumbcontact the slip-resistant portion 1. In this manner, the highcoefficient of friction allows the person 2 to lift the folder 1 withoutas tight a grip as would be necessary without slip-resistant portion 1.

In one embodiment, slip-resistant portion 1 can be affixed as a narrowband of material near the top edge of either or both the front and rearflaps of a folder. By “near the top edge” is meant within normal reachof a person's thumb or fingers when grasping a folder from the top, forexample to lift it out of a drawer. In particular, a band approximately6-25 mm (¼-1 inch) wide in an area 20-80 mm (about 1-3 inches) from thetop edge of the folder flap is currently considered optimal. The bandneed not extend the whole width of the folder, but should at least spanthe central portion of the width. In general, as shown in FIG. 2, as aperson grips a folder the thumb contacts one flap, while the fingerscontact the opposing flap. Having a slip-resistant portion on both flapsassures that both the thumb and fingers contact areas of highcoefficient of friction, making gripping easier. In certain embodiments,however, it is contemplated that having a slip-resistant portion on onlyone flap may be desirable.

As shown in FIG. 3, slip-resistant portion 1 may be any material 4 thathas a high coefficient of friction which is applied or affixed as alayer to front flap 22 or rear flap 24 (not shown). In a preferredembodiment, material 4 is a light-tack pressure-sensitive adhesiveapplied in a uniform layer as a horizontal stripe or band near the topedges of folder 10. By way of example, suitable light-tack adhesivesinclude adhesives of the type and tack used on Post-it® notes. Such anadhesive is tacky enough to give a high coefficient of friction betweena persons fingers and the folder, but not so tacky as to be a nuisanceduring normal use of the folder. Person's skilled in the art willrecognize that in addition to the examples provided above (i.e.,adhesives disclosed in US patents assigned to the Minnesota Mining andManufacturing Co.), a wide range of adhesives from numerous sourcescould be used or adapted for use as a slip-resistant portion. Theexamples given, therefore, are to be exemplary and not limiting.

Slip-resistant portion 1 may be discontinuous, such as stripes or dotsin a regular or random pattern, or a continuous network ofinterconnected beads or lines of adhesive, for example. By varying theamount and placement of slip-resistant material, the overall tackinessof slip-resistant portion 1 may be varied. If desired, a release strip 5may be supplied covering the light-tack adhesive, as shown in FIG. 3. Inthis manner, the end user may activate the slip-resistant feature atwill by removing all or part of the release strip 5.

If light-tack adhesive, or other pressure sensitive adhesive, is usedfor slip-resistant portion 1, it may be applied and cured in acontinuous process during manufacture of the folder 10 as describedbelow with reference to FIGS. 10-11. However, it is possible to adaptexisting folders to folders of the present invention. For example, asshown in FIG. 4, one method of producing a folder of the presentinvention is to add strips of light-tack adhesive in tape form to anexisting folder 10. As shown, a first strip of tape 6, such as a ¾-inchwide strip of 3M Scotch® double-coated tape 665 is applied to one flap,such as front flap 22. This tape, having adhesive on both sides, couldbe used alone, with the outwardly-facing side being of high coefficientof friction serving as the slip-resistant portion. However, the tack maytoo great, so to make a light-tack slip resistant portion, a secondstrip of tape 8 having a light-tack may be affixed to the first layer 6,such that the light-tack side is outwardly facing from the folder. Apreferred second strip 8 is ¾-inch 3M Scotch® Removable Magic® 811 tapewhich is advertised as having the same self-stick adhesive as Post-it®notes. Alternatively, by way of example, second strip 8 may comprisePost-it® 652 correction and cover-up tape, with the tacky side outwardlyfacing. Alternatively, existing folders may be adapted by simplyapplying a layer of reusable adhesive from a suitable glue stick, suchas Scotch® Restickable Adhesive Glue Stick, Cat. No. 06314, availablefrom 3M Consumer Stationery Division, St. Paul, Minn.

While one embodiment of slip-resistant portion 1 comprises a materialapplied or affixed to the front or back flaps of a folder 10, it neednot be so. For example, as shown in cross-section in FIG. 5,slip-resistant portion 1 may be made by mechanically deforming the paperstructure to form raised bumps or ridges. One method of deforming isembossing, in which the paper stock is pressed between forming dies tobe permanently deformed in the desired pattern. One pattern, as shown inFIG. 5, is a plurality of horizontal, generally parallel ridges andvalleys 9. The advantage of embossing, rather than applying adhesive, isthat the resulting slip-resistant portion is not tacky to the touch,eliminating any possible negative effects of having such a tackysurface. Persons skilled in the art will recognize that the possiblepatterns for embossing are virtually limitless. Certain preferredpatterns are shown in FIGS. 15 and 16. Therefore, the configurationdepicted in FIG. 5 is exemplary, and not limiting.

While the raised ridge-like structures shown in FIGS. 5, 15, and 16 arepreferably formed by embossing the paper stock during foldermanufacture, persons skilled in the art will recognize that othermethods and techniques may be employed with similar results. Forexample, the paper may be formed in the wet state and molded into theconfigurations shown. Furthermore, a separate paper or plastic stripwith embossed or molded ridges may be joined to a folder to formslip-resistant portion 1. For example, a thin plastic strip ofrelatively rigid polypropylene may be molded with suitably placedridges, and adhered to the folder in a suitable location. Therefore,embossing to form ridges or ridge-like structures is meant to beexemplary, even preferred, but not limiting.

When pressure-sensitive adhesive is used, the slip-resistant portion 1on the front flap 22 is preferably vertically offset a certain distancefrom the slip-resistant portion 1′ on the rear flap 24. In this regard,the “vertical” direction refers to the direction orthogonal to a topedge 25 of a folder flap, generally in the plane of the respectivefolder cover. As shown in FIG. 6, a vertical offset prevents theslip-resistant portions on the rear flap of one folder from interferingwith the slip resistant portion on the front flap of an adjacent folderin a drawer, possibly causing them to stick excessively to one another.FIG. 6 shows three folders 20 as they may be situated in relation to oneanother in a file drawer. Although file folders are shown, the principleshown holds for all types of folders, including file pockets and hangingfolders. The lower edge of slip-resistant portion 1 on front flap 22 isa distance D1 from top 25, whereas the upper edge of slip-resistantportion 1′ on rear flap 24 is a distance D2, greater than D1, from top25. In this manner, slip resistant portions of adjacent folders do notcontact one another, possibly causing unwanted sticking of adjacentfolders.

It is contemplated that if vertically-offset slip-resistant portions areused, as shown in FIG. 6, the slip-resistant portion on the front flapshould be the one closer to the top. This is because the front flap isusually contacted by the thumb of a person removing it, while the rearflap is contacted by the fingers. Since the fingers are longer than thethumb, they are more suited for the longer distance associated with thelonger distance D2.

The folder 10 shown in FIG. 7 is exemplary of a file pocket 30. Filepocket 30 comprises a front flap 32, and a rear flap 34, connected atthe bottom by folder bottom 36 comprising expandable fan folds, andpartially along the sides by expandable side members 38. File pocketshave top edges 35 on front and rear flaps that typically stand higherthan the enclosed papers, with a scored line 35 for bending down the topedges to gain easier access to enclosed papers. Such a configurationmakes gripping a full folder for removal more difficult since upongripping, the top flaps tend to bend inward into somewhat of a wedgeshape that is more difficult to grip.

File pocket 30 is shown in FIG. 7 with another preferred embodiment forslip-resistant portion 1, namely a slip-resistant portion that comprisesrecognizable designs or indicia 12, such as the manufacture's name. Byvarying the material and method of application of slip-resistant portion1, visible, aesthetically pleasing designs or indicia 12 may be applied,including letters, numbers, or other decorative or utilitarian markings.For example, printing methods known in the art may be employed to applycolored adhesives or high coefficient of friction polymeric materials invirtually limitless designs, locations, and amounts.

FIG. 8 depicts an expanding file 40, which along with expanding wallets,is distinguished primarily by its cover flap 49. Expanding file 40 has afront flap 42, a rear flap 44 connected at the bottom by expandablefolder bottom 46 and along the sides by expandable sides 48. Cover flap49 is typically secured in a closed position by a tie string, elasticcord, Velcro® hook and loop fasteners, or other securement means (notshown). Expanding files are often stored in file drawers or cabinets,and are often stored in a hanging folder. To aid in lifting expandingfile 40 from the top, slip-resistant portion 1 is applied, shown in thisembodiment as parallel beads 14 of light-tack pressure-sensitiveadhesive or high coefficient of friction polymeric material. Any numberof beads, or stripes, of material 14 may be applied, and they may or maynot be continuous along the full width of the folder. For example,stripes or beads of material may be applied in discontinuous segments asdesired.

The folder 10 shown in FIG. 9 is exemplary of a hanging folder 50.Hanging folder 50 generally comprises a front flap 52 connected to arear flap 54 by folder bottom 56, typically comprising a medial fold.Hanging folder 50 is primarily distinguished by hanging rods 59, whichare movably or immovably fixed to top edges 55. The ends of rods 59 areexposed and notched, enabling the file to hang on a complementarystandard parallel file frame in filing drawers or cabinets. As shown inthe embodiment depicted in FIG. 8, slip-resistant portion 1 may beapplied in a discontinuous manner, for example in a regular pattern ofspaced apart dots. The dots may be a separate material, such asfine-grit abrasive paper affixed by adhesive. In general, however, thedots are preferably comprised of light-tack adhesive or high coefficientof friction polymeric material applied by any suitable manner duringmanufacture of folder 10.

The slip-resistant portion embodiment shown in FIG. 9 may also representraised bumps formed by embossing the paper stock in the area of the slipresistant portion. One desirable embodiment contemplated is to form apattern of closely-spaced raised bumps with light-tack adhesive disposedin the non-raised areas surrounding the bumps. For example, a pattern ofembossed “dimples” could be superposed on a pattern of adhesive suchthat the raised bumps do not have adhesive on them. A slip-resistantportion of this type would not feel tacky to the touch, but uponapplying pressure to the raised bumps, they could collapse, so that aperson's fingers would then contact the adhesive disposed around thebumps. In this manner, the tackiness would not be “activated” untilneeded by the user. Alternatively, the bumps need not be collapsible;the persons finger tips could simply press in around the bumps,contacting the slip-resistant material.

The slip-resistant portion shown in FIG. 9 may also represent holes, orslits, formed by very deep embossing, or by die punching. Deep embossingwhich actually causes penetration of the flap to form raised ridges maybe provided as long as the flap integrity is maintained. Likewise, holesor slits made by die cutting may provide sufficient friction to act as aslip-resistant portion without the need for adhesives or polymericmaterials.

The slip-resistant portion 1 shown in FIG. 9 may also represent anembodiment wherein slip-resistant portion 1 comprises a paper or plasticstrip having molded-in bumps, holes, or other raised areas. The paper orplastic strip can be made separately by methods known in the art, andthen joined to the folder to form a folder of the present invention. Forexample, thin strips of injection molded polypropylene could be formedand adhered to the folder.

Hanging folders come in a wide range of sizes and configurations, all ofwhich may benefit by the improvement of the present invention. Forexample, in FIG. 10, a flat bottom, or box-bottom, hanging folder 60 isshown. Box-bottom hanging folder 60 generally comprises a front flap 62connected to a rear flap 64 by a flat, horizontal folder bottom 66.Box-bottom hanging folder 60 has hanging rods 69, which are movably orimmovably fixed to top edges 65. Sides 68 are often not present, but ifpresent they may be expandable, and are often reinforced for durability.As shown in the embodiment depicted in FIG. 10, slip-resistant portion 1may be comprised of a continuous network of interconnected lines 16 ofslip-resistant material. Person's skilled in the art will recognize thatthe variations in continuous networks of interconnected lines arevirtually limitless, and the embodiment shown is exemplary and notlimiting.

Also shown in FIG. 10 is another beneficial advantage of the presentinvention. When slip-resistant portion 1 is applied as a light tackadhesive, such as an adhesive similar to the adhesive used on Post-it®notes, the slip-resistant portion 1 may serve a note-posting fraction.Notes 18 may be conveniently and removably stuck to folder 10 on theslip-resistant portion 1. When used for this fraction, it may even bedesirable to place the light-tack adhesive on other parts of the folder10, including on the inside.

Often reinforcing plastic film is applied to the top edges of folders.For example, hanging folders have reinforced plastic laminates foldedwith the paper stock enclosing the hanging rods, which serve to make thehanging folder more durable and wear resistant. One embodiment of thepresent invention contemplated is to combine the reinforcing laminatematerial of such folders with the slip-resistant portion 1 of thepresent invention. In such an embodiment plastic materials with a highcoefficient of friction could be chosen as the reinforcing laminatematerial at the top edges of the folders. By doing so, theslip-resistant portion is “built-in” to a material having a separateprimary function, thereby eliminating or reducing any costs associatedwith adding a separate material for slip-resistant material 1.

In an alternative embodiment, a separate member, such as an injectionmolded plastic strip can be preformed and affixed to the flaps of afolder. For example, a thin plastic strip can be molded to have raisedridges, bumps, or other gripping surfaces. The strip can then be joinedto the folder by methods known in the art. Thus, an existing folder canbe easily converted to a slip resistant file folder by the applicationof the molded strip to the folder, such as by adhesive.

As stated above, one method for applying slip-resistant portion 1 is tomanually apply light-tack adhesive tape to an existing folder 10.However, commercially viable processes are preferred, such as arotogravure printing process, schematically depicted in FIG. 11. Otherprinting processes and configurations known in the art may be used asnecessary for particular manufacturing considerations, but therotogravure process is described here as a preferred method. In general,such processes apply an adhesive or polymeric material in the melt statewhich is subsequently cured or dried to a substantially solid layer. By“melt state” is meant hot melt as well as liquid state materialtemporarily having low viscosity to allow for application by printing,spraying, extrusion, or other application methods known in the art.

As shown in FIG. 11, folder paper stock 71 may be conveyed on amanufacturing line, such as conveyor 72 in a generally flat-outconfiguration during a continuous manufacturing process 70. While beingconveyed in such a process, the paper stock is passed to a heatedrotogravure printing station comprising a backing roll 76 and engravedroll 77, at which point a curable slip-resistant material, such as alight-tack, hot melt processible adhesive, is applied to one surface ofthe folder paper stock in a predetermined area and pattern. Theslip-resistant material is then cured, dried, or otherwise substantiallysolidified to form the slip-resistant portion 1. For example, curingstation 73 may be positioned to cure by UV radiation or IR radiant heat,depending on the particular slip-resistant material used. Othercompositions, such as high coefficient of friction polymers may beapplied in a liquid polymer state in similar fashion, then cured ordried by suitable means known in the art to form slip-resistant portion1.

During the printing process, the slip-resistant material, is supplied toa heated supply tank 78 and pumped to the heated doctor application head79 by a suitable metering pump. It is generally desirable to maintainconstant temperature during the process; therefore, it is desirable tocontinually circulate the melted composition between the supply tank andthe application head while maintaining an adequate amount in thereservoir. The heated doctor application head supplies theslip-resistant material to the engraved roll, the surface of which isengraved with the desired pattern for slip-resistant portion 1.

In operation the engraved roll is loaded to the backing roll to forcethe paper stock into contact with the engraved roll. The backing rollcan be any material that meets the process requirements such as naturalrubber, synthetic rubber or other compressible surfaces. Loadingpressures can vary, depending on paper stock thickness, compositionthickness, and processing speeds.

If necessary, post-application processing for curing or otherwisesubstantially solidifying the slip-resistant material, such as UVcuring, radiant heat drying, or other steps may be employed. Specificprocessing steps necessary for particular melt processible adhesives areknown in the art and the steps disclosed may be modified, added to, orotherwise changed in ways that do not depart from the scope of thepresent invention. For example, melt processing comprising extrusion maybe advantageously employed for certain adhesives or polymers.

Additionally, continuous layers of slip-resistant material, such aslight-tack adhesives or high coefficient of friction liquid polymermaterials, may be applied by spraying in predetermined patterns, forexample by the process schematically depicted in FIG. 12. Again folderpaper stock 71 may be conveyed on a manufacturing line, such as endlessconveyor 72 in a generally flat-out configuration during a continuousmanufacturing process 70. A spray nozzle 75, or other suitable die, maybe set up in position to intermittently spray a pattern of curableadhesive 74 or other curable polymeric material at predeterminedpositions, according to the various embodiments of the presentinvention. Further processing to cure, such as UV curing, radiant heattrying, and other advantageous processing steps may be employed asnecessary for specific processes and equipment. As well, other sprayprocesses and techniques may be used without departing from the scope ofthe present invention.

Permanent mechanical deformation can be accomplished by the use ofopposing, mating dies, such as embossing dies 80 shown in FIG. 13. Manymethods known in the art for embossing, stamping, or otherwise pressingpaperboard can be used to form the ridges and valleys 9 that make up theslip resistant portion 1. In FIG. 13, an upper die 82, and a lower die81 in operative, spaced relationship. The dies may be operative in alinear, reciprocating relationship essentially in the y-axis such thatthey operate in a stamping motion. Teeth 84 mate in a male/femalerelationship to effect the deformation of the paperboard of flap 22. Inthis type of embossing, each flap 22 could be placed between dies 81,82, pressed or stamped, and then removed. Alternatively folded or flatpaper stock could be fed continuously on a manufacturing line as dies81, 82 operate in a repetitive, timed, cyclical motion to emboss thefolders during continuous manufacturing.

FIG. 14 shows schematically another method of continuous embossing.Embossing dies 80 are in the form of mating ridged rollers 81, and 82that can have the general cross section as dies 80 of FIG. 13. As paperstock for flap 22 is conveyed in the manufacturing process, for examplein the z-direction as shown in FIG. 14, it moves through the matingrollers, becoming embossed in a continuous fashion.

The apparatus depicted schematically in FIG. 14 provides for high speedembossed ridges and valleys, and can be carried out by the apparatusshown and described in U.S. Pat. No. 5,691,035 issued Nov. 25, 1997 toChappell et al. and hereby incorporated herein by reference. Inparticular, it is possible to modify the mating dies in ways that impartunique patterns of ridges and undeformed regions to form slip resistantportions 1. For example, by utilizing embossing dies in the formillustrated in FIG. 36 of the aforementioned Chappell et al. patent, aslip resistant portion 1 generally as shown in FIG. 15 can be formed. Asshown in FIG. 15, slip resistant portion 1 is comprised of spaced setsof raised ridges 98 separated by undeformed portions 99. Undeformedportions 99 can be made various dimensions such that they providestructural support to flap 92, while ridges 98 provide for a highcoefficient of friction for slip resistance.

In like manner, dies 80 can be modified to provide for other patterns ofridges and undeformed regions. In one embodiment, as depicted in FIG.16, the undeformed regions can be shaped in the form of indicia,including letters, numbers, logos, and other identifying indicia.

While the above description contains many specificities, these shouldnot be construed as limitations on the scope of the invention, butrather as illustrative of exemplary and preferred embodiments thereof.Many other variations are possible without departing from the spirit andscope of the invention as disclosed. For example, additional folds offlap material near top edges may be sufficient to form a slip-resistantportion. Accordingly, it is intended to cover in the appended claims allsuch variations, changes, and modifications that are within the scope ofthis invention.

1. A method of making a slip-resistant folder, said folder having afront flap having a first top edge, a rear flap connected to said frontflap by a folder bottom, said rear flap having a second top edge, and aslip-resistant portion disposed on at least one of said flaps near saidfirst or second top edge, said method comprising the steps of: (a)providing folder paper stock; (b) conveying said folder paper stock inthe process of folder manufacture; (c) providing a curableslip-resistant material in a melt state; (d) applying saidslip-resistant material at predetermined areas of said folder paperstock; and (e) curing said slip-resistant material; such that saidslip-resistant portion comprises cured slip-resistant material.
 2. Themethod of claim 1, wherein said applying is by a method of printing. 3.The method of claim 1, wherein said applying is by a method of spraying.4. A method of making a slip-resistant folder, said folder having afront flap having a first top edge, a rear flap connected to said frontflap by a folder bottom, said rear flap having a second top edge, and aslip-resistant portion disposed on at least one of said flaps near saidfirst or second top edge, said method comprising the steps of: (a)providing folder paper stock; (b) providing embossing dies in spaced,operable, mating relationship; (c) positioning said folder paper stockappropriately in said embossing dies; (d) applying force to at least oneof said embossing dies so as to decrease the spaced relationship; and(e) deforming said folder paper stock.
 5. The method of claim 4 furtherincluding the step of applying curable slip resistant material to atleast a portion of said deformed places to increase slip resistance. 6.The method of claim 5 wherein said material is applied by spraying. 7.The method of claim 5 wherein said material is applied by printing.